Solving probabilities that involves percentage.

I'm weak when it comes to solving probability questions that has to do with percentage. please help me.

1. Muscular dystrophy is a genetically controlled disease. The probability of having this disease in any new born of a specific parents is 25%. If the couple has 5 children, find the probabilities that:
(a) 5 will have a muscular dystrophy
(b) Fewer than 2 will have a muscular dystrophy

2. If 20% of the bolts produced by a machine are defective, determine the probability that out of 4 bolts:
(a) 1 is defective
(b) None of the bolts is defective
At most 2 bolts will be defective

Re: Solving probabilities that involves percentage.

Originally Posted by fara

I'm weak when it comes to solving probability questions that has to do with percentage. please help me.

1. Muscular dystrophy is a genetically controlled disease. The probability of having this disease in any new born of a specific parents is 25%. If the couple has 5 children, find the probabilities that:
(a) 5 will have a muscular dystrophy
(b) Fewer than 2 will have a muscular dystrophy

2. If 20% of the bolts produced by a machine are defective, determine the probability that out of 4 bolts:
(a) 1 is defective
(b) None of the bolts is defective
At most 2 bolts will be defective

tq

a) Each child has a 1/4 chance of getting the disease, so the probability of all of them having the disease is 1/4 x 1/4 x 1/4 x 1/4 x 1/4 = (1/4)^5.

Re: Solving probabilities that involves percentage.

Originally Posted by fara

1. Muscular dystrophy is a genetically controlled disease. The probability of having this disease in any new born of a specific parents is 25%. If the couple has 5 children, find the probabilities that:
(a) 5 will have a muscular dystrophy
(b) Fewer than 2 will have a muscular dystrophy

2. If 20% of the bolts produced by a machine are defective, determine the probability that out of 4 bolts:
(a) 1 is defective
(b) None of the bolts is defective
At most 2 bolts will be defective
tq